scholarly journals Intergrowth Structures in Synthetic Pyrochlores: Implications for Radiation Damage Effects and Waste Form Formulation

1999 ◽  
Vol 556 ◽  
Author(s):  
E. C. Buck ◽  
D. B. Chamberlain ◽  
R. Gieré
Keyword(s):  
Radiation Damage ◽  
Volume Expansion ◽  
Stress Relief ◽  
Waste Form ◽  
Ceramic Waste ◽  
Waste Forms ◽  
Defense In Depth ◽  
Intergrowth Structures

AbstractTitanate-based ceramic waste forms are currently under development for the immobilization of excess weapons plutonium. Both Hf and Gd are added to the ceramic formulation as neutron absorbers in order to satisfy a defense-in-depth concept for the waste form. The introduction of significant amounts of hafnium may be responsible for the presence of zirconolite-2M crystals in pyrochlore-based ceramics and the formation of zirconolite lamellae within pyrochlore. The zirconolite grows epitaxially on { 111 }planes of pyrochlore. Although the zirconolite lamellae within pyrochlore are non-cubic, any volume expansion due to radiation damage in the pyrochlore should still be isotropic; in addition, the presence of these intergrowths may allow some stress relief in the ceramic.

Aging Studies of Pu-238 and -239 Containing Calcium Phosphate Ceramic Waste-forms

2013 ◽  
Vol 1518 ◽  
pp. 73-78 ◽  
Author(s):  
Shirley K. Fong ◽  
Brian L. Metcalfe ◽  
Randall D. Scheele ◽  
Denis M. Strachan
Keyword(s):  
Calcium Phosphate ◽  
Accelerated Aging ◽  
Waste Form ◽  
Calcium Phosphate Ceramic ◽  
Ceramic Waste ◽  
Waste Forms ◽  
Aging Studies ◽  
Flow Through ◽  
Pyrochemical Reprocessing

ABSTRACTA calcium phosphate ceramic waste-form has been developed at AWE for the immobilisation of chloride containing wastes arising from the pyrochemical reprocessing of plutonium. In order to determine the long term durability of the waste-form, aging trials have been carried out at PNNL. Ceramics were prepared using Pu-239 and -238, these were characterised by PXRD at regular intervals and Single Pass Flow Through (SPFT) tests after approximately 5 yrs.While XRD indicated some loss of crystallinity in the Pu-238 samples after exposure to 2.8 x 1018 α decays, SPFT tests indicated that accelerated aging had not had a detrimental effect on the durability of Pu-238 samples compared to Pu-239 waste-forms.

Progress on Ongoing Waste form HIP projects at ANSTO

MRS Advances ◽  
2018 ◽  
Vol 3 (20) ◽  
pp. 1059-1064 ◽  
Author(s):  
Eric R. Vance ◽  
Dorji T. Chavara ◽  
Daniel J. Gregg
Keyword(s):  
Spent Nuclear Fuel ◽  
Technology Development ◽  
Hot Isostatic Pressing ◽  
Waste Form ◽  
Process Technology ◽  
Ceramic Waste ◽  
Waste Forms ◽  
Produce Glass ◽  
Form Development ◽  
Year 2000

Abstract:Since the year 2000, Synroc has evolved from the titanate full-ceramic waste forms developed in the late 1970s to a hot isostatic pressing (HIP) technology platform that can be applied to produce glass, glass–ceramic, and ceramic waste forms and where there are distinct advantages over vitrification in terms of, for example, waste loading and suppressing volatile losses. This paper describes recent progress on waste form development for intermediate-level wastes from 99Mo production at ANSTO, spent nuclear fuel, fluoride pyroprocessing wastes and 129I. The microstructures and aqueous dissolution results are presented where applicable. This paper provides perspective on Synroc waste forms and recent process technology development in the nuclear waste management industry.

Performance Assessment of Zircon as a Waste Form for Excess Weapons Plutonium Under Deep Borehole Burial Conditions

1995 ◽  
Vol 412 ◽  
Author(s):  
W. J. Weber ◽  
R. C. Ewing ◽  
W. Lutze
Keyword(s):  
Performance Assessment ◽  
Radiation Damage ◽  
Alpha Decay ◽  
Chemical Durability ◽  
Waste Form ◽  
Accessory Mineral ◽  
Deep Borehole ◽  
Waste Forms ◽  
Weapons Grade Plutonium ◽  
Precambrian Terranes

AbstractZircon (ZrSiO4) is proposed as a waste form for excess weapons-grade plutonium. Zircon is an extremely durable ceramic that is often found as an accessory mineral in Precambrian terranes with ages up to 4 billion years. The chemical durability of zircon in groundwater far exceeds that of other waste forms, as modeled leach rates may be as low as 10-11g/m2d. At least 10 wt% Pu can substitute for Zr in zircon. Self-radiation damage from alpha decay leads to a crystalline-to-amorphous transformation that is modeled as a function of time and temperature for deep borehole conditions. Based on the results of this assessment, zircon could meet all necessary durability and criticality criteria required for a Pu waste form. The types of data used in this analysis are generally not available for other crystalline ceramics or glasses.

scholarly journals Radiation damage of hollandite in multiphase ceramic waste forms

2017 ◽  
Vol 494 ◽  
pp. 61-66 ◽  
Author(s):  
Braeden M. Clark ◽  
Priyatham Tumurgoti ◽  
S.K. Sundaram ◽  
Jake W. Amoroso ◽  
James C. Marra ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Ceramic Waste ◽  
Waste Forms

A Single Phase ([Nzp]) Ceramic Radioactive Waste Form

1982 ◽  
Vol 15 ◽  
Author(s):  
Rustum Roy ◽  
L.J. Yang ◽  
J. Alamo ◽  
E.R. Vance
Keyword(s):  
Radioactive Waste ◽  
Single Phase ◽  
Waste Form ◽  
Chemical Model ◽  
Crystal Chemical ◽  
Ceramic Waste ◽  
Molar Ratios ◽  
Loading Level ◽  
Waste Forms ◽  
Waste Loading

ABSTRACTIt has been shown that between 10 and 20% of a simulated PW–4b radwaste composition can be incorporated into a single nhase with the NZP (= ‘MaZr2 P3 o12’) structure. By changing the P/Na and Zr/Na molar ratios (i.e., adjusting the crystal chemical model of where each ion is located in the structure) it has been possible to outline a very ‘forgiving’ compositional regime both at the 10% and the 20% waste loading level within which one obtains one ([NZP]) or two ([NZP] and [monazite]) phases. We have also succeeded in substituting Tio2 for Zro2 in making a TiO2-rich [NTP] waste form analogous to the [NZ]] materials.Thus we have succeeded in creating monophasic and diphasic ceramic waste forms which can be sintered below 1000° C. Only preliminary leach data have been obtained at 25° and 300°C, and they place this material with good ceramic forms.

scholarly journals Synroc development—Past and present applications

2017 ◽  
Vol 4 ◽  
Author(s):  
Eric R. Vance ◽  
Dorji T. Chavara ◽  
Daniel J. Gregg
Keyword(s):  
Glass Ceramic ◽  
Intermediate Level ◽  
Waste Form ◽  
Spent Fuel ◽  
Process Technology ◽  
Technology Platform ◽  
Ceramic Waste ◽  
Waste Forms ◽  
Produce Glass ◽  
Waste Loading

ABSTRACTSynroc has evolved over the last 40 years from the titanate full-ceramics developed in the late 1970s to a technology platform that can be applied to produce glass, glass–ceramic, and ceramic waste forms and where there are distinct advantages in terms of waste loading and suppressing volatile losses.A first of a kind Synroc plant for immobilizing intermediate level waste arising from Mo-99 production is currently in detailed engineering at ANSTO.Since the year 2000, Synroc has evolved from the titanate full-ceramics developed in the late 1970s to a technology platform that can be applied to produce glass, glass–ceramic, and ceramic waste forms and where there are distinct advantages in terms of waste loading and suppressing volatile losses. Furthermore recent efforts have focused strongly on waste form development for plutonium-bearing wastes in the UK, for different options for the immobilization of Idaho calcines and most recently developing an engineered waste form for the intermediate level wastes arising from 99Mo production, for the Australian Nuclear Science and Technology Organisation (ANSTO). A variety of other studies are currently in progress, including engineered waste forms for spent fuel and investigating the proliferation risks for titanate-based waste forms containing highly enriched uranium or plutonium. This paper also attempts to give some perspective on Synroc waste forms and process technology development in the nuclear waste management industry.

Synroc tailored waste forms for actinide immobilization

2017 ◽  
Vol 105 (11) ◽  
Author(s):  
Daniel J. Gregg ◽  
Eric R. Vance
Keyword(s):  
Glass Ceramic ◽  
Waste Treatment ◽  
Waste Form ◽  
Borosilicate Glasses ◽  
Process Technology ◽  
Treatment Technology ◽  
Ceramic Waste ◽  
Waste Forms ◽  
Glass Matrices ◽  
Key Aspects

AbstractSince the end of the 1970s, Synroc at the Australian Nuclear Science and Technology Organisation (ANSTO) has evolved from a focus on titanate ceramics directed at PUREX waste to a platform waste treatment technology to fabricate tailored glass–ceramic and ceramic waste forms for different types of actinide, high- and intermediate level wastes. The particular emphasis for Synroc is on wastes which are problematic for glass matrices or existing vitrification process technologies. In particular, nuclear wastes containing actinides, notably plutonium, pose a unique set of requirements for a waste form, which Synroc ceramic and glass-ceramic waste forms can be tailored to meet. Key aspects to waste form design include maximising the waste loading, producing a chemically durable product, maintaining flexibility to accommodate waste variations, a proliferation resistance to prevent theft and diversion, and appropriate process technology to produce waste forms that meet requirements for actinide waste streams. Synroc waste forms incorporate the actinides within mineral phases, producing products which are much more durable in water than baseline borosilicate glasses. Further, Synroc waste forms can incorporate neutron absorbers and

scholarly journals Preparation and characterization of multiphase ceramic designer waste forms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Braeden M. Clark ◽  
Priyatham Tumurugoti ◽  
Shanmugavelayutham K. Sundaram ◽  
Jake W. Amoroso ◽  
James C. Marra
Keyword(s):  
Fixed Ratio ◽  
Chemical Durability ◽  
Waste Form ◽  
Ceramic Waste ◽  
Waste Forms ◽  
Plasma Sintering ◽  
Long Term Performance ◽  
Term Performance ◽  
Elemental Release

AbstractThe long-term performance, or resistance to elemental release, is the defining characteristic of a nuclear waste form. In the case of multiphase ceramic waste forms, correlating the long-term performance of multiphase ceramic waste forms in the environment to accelerated chemical durability testing in the laboratory is non-trivial owing to their complex microstructures. The fabrication method, which in turn affects the microstructure, is further compounding when comparing multiphase ceramic waste forms. In this work, we propose a “designer waste form” prepared via spark plasma sintering to limit interaction between phases and grain growth during consolidation, leading to monolithic high-density waste forms, which can be used as reference materials for comparing the chemical durability of multiphase waste forms. Designer waste forms containing varying amounts of hollandite in the presence of zirconolite and pyrochlore in a fixed ratio were synthesized. The product consistency test (PCT) and vapor hydration test (VHT) were used to assess the leaching behavior. Samples were unaffected by the VHT after 1500 h. As measured by the PCT, the fractional Cs release decreased as the amount of hollandite increased. Elemental release from the zirconolite and pyrochlore phases did not appear to significantly contribute to the elemental release from the hollandite phase in the designer waste forms.

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